Faintly aromatic cushioning body

ABSTRACT

A faintly aromatic cushioning body comprising: a mixture of expanded resin beads and aroma-containing beads, the expanded resin beads having a solvent of 400 ppm or less and an average particle diameter of 0.4 to 1.4 mm, wherein the mixture of expanded resin beads and aroma-containing beads is used as a filler into a bag.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to Japanese application No. 2004-89660 filed on Mar. 25, 2004, whose priority is claimed under 35 USC § 119, the disclosure of which is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a faintly aromatic cushioning body. More particularly, it relates to a faintly aromatic cushioning body which can be suitably used as a bed, a mattress, a pillow, a stuffed toy, a cushion, a toy, a cushioning medium and the like, which have a faint aroma.

2. Description of Related Art

As conventional cushioning bodies, cushioning bodies using cotton, feathers, non-rigid urethane foam, resin beads and the like are generally known. Among these, as cushioning bodies using resin beads, Japanese Examined Utility Model Publication No. HEI 3(1991)-45641 discloses a cushioning body in a matt form using as fillers styrene foam beads of various diameters in the range of about 1 to 5 mm and Japanese Unexamined Utility Model Publication No. SHO 56(1981)-115966 discloses a cushioning body using as fillers expanded beads of polystyrene or the like having a diameter of 5 to 20 mm.

Meanwhile, there are reported cushioning bodies provided with an aroma in order to induce sleep or for a relaxation or aromatherapy effect. For example, Japanese Unexamined Utility Model Publication No. HEI 6(1994)-50570 discloses a cushioning body (a pillow) with a pillow cover in which an aromatic agent having a hypnotic effect of inducing sleep is inserted in a pocket attached to the pillow cover. This cushioning body is considered to have an effect in curing insomnia or changing the condition for the better by an aroma emitted from the pocket. This publication has no description on the constitution of fillers themselves contained in the pillow.

Further, Japanese Utility Model Registration No. 3082132 reports an aromatic mascot which is not a cushioning body. In this pocket-shaped mascot, an aroma bag containing an aromatic agent is inserted. This publication describes an aromatic agent prepared by impregnating either granular vermiculite or baked vermiculite with an aromatic and also describes an aroma bag made of a polyethylene thin film with a breathable mesh.

The cushioning bodies in Japanese Examined Utility Model Publication No. HEI 3(1991)-45641 and Japanese Unexamined Utility Model Publication No. SHO 56(1981)-115966 have a problem that, when used as a bed, a mattress, a pillow, a cushion or the like which cushions a human body, the cushioning bodies cause an unusual sound every time a human body moves to give the user discomfort or wake the user to the unusual sound while he is in bed. Further, there is a definite demand for improvement in the feel of cushioning bodies when the cushioning bodies are in use. However this demand is not yet satisfied fully by any cushioning bodies provided so forth.

Also, in order to given the aroma to the cushioning body, in the constitution that the cushioning body is wrapped with the cover having the pocket filled with the aromatic agent or that the cushioning body is provided with the aroma bag containing the aromatic agent, the aroma intensity in the vicinity of the pocket or aroma bag may be different in aroma intensity of the position at a distance from the pocket or aroma bag, so that the cushioning body may not evenly generate the aroma. Further, the cushioning body may not have a desired aroma, since it has other smell than an aroma from the aromatic agent.

SUMMARY OF THE INVENTION

As a result of extensive study for solving these problems, the present inventors surprisingly found that, by using as a filler a mixture of expanded resin beads having a low content of solvent and aroma-containing beads and sealing the mixture into a bag, there can be provided a faintly aromatic cushioning body which has an aroma capable of exhibiting a relaxation or aromatherapy effect as well as a preferable touch or feel and in which occurrence of an unusual sound is suppressed, thus arriving at the present invention.

These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, there is provided a faintly aromatic cushioning body comprising: a mixture of expanded resin beads and aroma-containing beads, the expanded resin beads having a solvent of 400 ppm or less and an average particle diameter of 0.4 to 1.4 mm, wherein the mixture of expanded resin beads and aroma-containing beads is used as a filler into a bag.

The present inventors examined fillers made of expanded resin beads in conventional cushioning bodies to find that the conventional expanded resin beads are manufactured using preliminary expanded beads intended for exclusive use in foam molding.

That is, in general, expandable beads comprising a thermoplastic resin for use in foam molding has solvents such as toluene, ethylbenzene and the like added thereto so that foam molding is promoted. In their expandable beads including such solvents, a considerable amount of solvents remain even at the stage where the expandable beads have been changed to expanded resin beads (preliminary expanded beads). For this reason, when the expanded resin beads are used as fillers of a cushioning body, a smell of solvents from the cushioning body is perceived. Further, when polystyrene is used as resin other than these solvents, a smell of styrene monomers or the like which are residual in the resin is generated as well.

Especially in an aromatic cushioning body, a smell of solvents is mixed with an aroma of an aromatic agent so that a smell different from an originally expected aroma is generated. Thus, the smell of solvents is obviously a cause to inhibit the aroma which exhibits a relaxation or aromatherapy effect.

According to the present invention, since the expanded resin beads having a solvent content of 400 ppm or less are used as fillers, the occurrence of a smell of the solvent from the cushioning body is suppressed. Also, since the expanded resin beads have an average particle diameter of 0.4 to 1.4 mm, the cushioning body can be endowed with a good touch while suppressing generation of an unusual sound from the cushioning body. Further, since the expanded resin beads and the aroma-containing beads are sealed into the bag, an aroma can be generated evenly from the cushioning body.

Hereafter, the present invention is explained more specifically.

The faintly aromatic cushioning body of the present invention comprises a bag and fillers sealed into the bag. The fillers comprise expanded resin beads and aroma-containing beads.

The average particle diameter of the expanded resin beads is 0.4 to 1.4 mm, among which expanded resin beads having an average particle diameter of 0.5 to 1.3 mm are preferably used to prevent occurrence of an unusual sound and to give a more preferable feel. The average particle diameter is more preferably 0.5 to 0.85 mm. An average particle diameter of smaller than 0.4 mm is not preferable because the expanded resin beads leak out from a crevice formed in the bag or from between fibers. Also, an average particle diameter of greater than 1.4 mm is not preferable because the touch is degraded and the unusual sound is prone to occur. Further, the expanded resin beads are more preferably those having the above average particle diameter and substantially free of beads having a particle diameter greater than 2 mm in order to exhibit particularly outstanding effects for prevention of an unusual sound and for a more preferable feel. The method of measuring the average particle diameter is described in the examples.

The reason why the occurrence of the unusual sound can be suppressed and the more preferable touch can be given is considered to be as follows. The present inventors extensively examined the reason that the expanded resin beads having a large particle diameter for foam molding are inferior in the touch and feel when used as fillers in cushioning bodies. As a result, they found that the conventionally used expanded resin beads are large and hardly slide mutually so that during use, the beads while remaining poor in the touch and feel are merely deformed so as to reduce the volume by compression.

Further, they found that when the large and hardly sliding expanded beads are used, an unusual sound easily occurs.

As a result of extensive study for solving these problems, the present inventors surprisingly found that when expanded resin beads having a specific average particle diameter are made flowable, that is, easily sliding mutually by very small strength, the expanded resin beads can be provided as those for exclusive use in cushioning bodies, with significant improvements in the touch and feel. These expanded resin beads can be used as fillers in cushioning bodies to prevent occurrence of an unusual sound, to exhibit a preferable touch and to achieve permanent cushioning properties.

The expanded resin beads are not particularly limited as long as they are made of resin having a solvent content of 400 ppm or less, and the expanded resin beads may be those made of styrene-based resin, polyethylene-based resin, polypropylene-based resin or the like. By using the expanded resin beads having the above content of solvent, the occurrence of a smell inhibiting a relaxation or aromatherapy effect owing to mixed smell of the solvent and a scent of the aromatic agent can be prevented. The content of solvent considered contributable to a sick-house syndrome and a chemical-substance hypersensitivity can be significantly reduced, thus a faintly aromatic cushioning body which is more suitable for a very small number of people sensitive to these solvents can provide. Expanded resin beads having a solvent content of higher than 400 ppm is not preferable because a smell of solvent to cause discomfort is perceived from the cushioning body. From these viewpoints, the content of solvent is preferably as low as possible, and specifically the content of solvent is more preferably 300 ppm or less, still more preferably 150 ppm or less, further still more preferably nearly 0. Examples of the solvent include residual styrene type monomers, toluene, ethylbenzene, cumene, xylene, n-propylbenzene and the like. The method of measuring the solvent content is described in the Examples.

The expanded resin beads are made preferably of styrene-based resin to achieve a more preferable feel.

To reduce the amount of residual styrene type monomers in the expanded resin beads when the expanded resin beads are prepared by suspension polymerization, a method may be used in which a polymerization initiator of high-temperature initiation type is used in an amount of 0.05% or more by weight based on styrene monomers, the final polymerization temperature is 115° C. or more, and the styrene monomers are let stand at this temperature for 2 hours or more for example.

The polymerization initiator of high-temperature initiation type is particularly preferably the one giving a half-life of 10 hours at a temperature of 100 to 115° C., such as t-butyl peroxybenzoate, t-butyl peroxypivalate, t-butyl peroxyisopropyl carbonate, t-butyl peroxyperoxyacetate and 2,2-t-butyl peroxybutane.

To reduce the amount of solvent such as toluene, ethylbenzene, cumene, xylene, n-propylbenzene or the like, it is preferable to choose styrene monomer containing these in a low content.

An expanding agent used in preparing the expanded resin beads is not particularly limited, and examples thereof include aliphatic hydrocarbons such as propane, n-butane, iso-butane, n-pentane, iso-pentane, neo-pentane, hexane and the like; alicyclic hydrocarbons such as cyclobutane, cyclopentane and the like; and inorganic expanding agents such as CO₂ gas, nitrogen, air and the like. These expanding agents can be used alone, or two or more thereof can be simultaneously used, and particularly those expanding agents as odorless as possible are used preferably as a major component in consideration of their influence on the aroma.

The amount of the expanding agent is preferably about 1 to 20 parts by weight based on 100 parts by weight of the resin beads and more preferably about 3 to 10 parts by weight. The amount of the expanding agent smaller than 1 part by weight is not preferable because the expanding agent does not fulfill its function. Also, the amount of the expanding agent greater than 20 parts by weight is not preferable either because the expanding agent may have too great an influence on the aroma. When CO₂ gas is used as the expanding agent, the pressure for impregnation with the expanding agent is 10 to 30 kg/cm²G, and the impregnation time is preferably about 1 to 10 hours.

To obtain the expanded resin beads, a nucleating agent may be added during polymerization and/or impregnation of the expanding agent to add the nucleating agent can be controlled the number of bubble. The amount of the nucleating agent to be added is regulated suitably to attain the desired number of bubbles, and usually its amount is 0.005 to 1 part by weight based on 100 parts by weight of the resin beads. The number of bubbles can also be regulated by selecting the type and amount of the expanding agent.

When the expanded resin beads are made of styrene-based resin beads, the styrene type monomers may be used in the resin beads include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, p-ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, p-n-butylstyrene, p-t-butylstyrene, p-n-hexylstyrene, p-octylstyrene, styrenesulfonic acid and sodium styrenesulfonate.

Further, it is also possible to simultaneously use various vinyl compounds, for example C₁₋₁₀ alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and 2-ethylhexyl acrylate; C₁₋₁₀ alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate and 2-ethylhexyl methacrylate; unsaturated compounds having a hydroxyl group, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate and hydroxybutyl methacrylate; unsaturated compounds containing a nitrile group, such as acrylonitrile and methacrylonitrile; organic acid vinyl compounds such as vinyl acetate and vinyl propionate; unsaturated monoolefins such as ethylene, propylene, 1-butene, 2-butene and isobutene; diene compounds such as butadiene, isoprene and chloroprene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; N-vinyl compounds such as N-vinyl pyrrolidone, N-vinyl indole, N-vinyl carbazole and N-vinyl pyrrole; unsaturated compounds having an amide group, such as acrylamide, methacrylamide, N-methylol acrylamide and N-methylol methacrylamide; unsaturated carboxylic acids such as acrylic acid, methacrylic acid and itaconic acid; maleimide compounds such as N-phenyl maleimide, N-(methyl)-phenyl maleimide, N-(hydroxy)phenyl maleimide, N-(methoxy)phenyl maleimide, N-benzoic acid maleimide, N-methyl maleimide, N-ethyl maleimide, N-n-propyl maleimide, N-isopropyl maleimide, N-n-butyl maleimide, N-isobutyl maleimide and N-t-butyl maleimide; crosslinking multifunctional vinyl compounds such as divinyl benzene and ethylene glycol dimethacrylate; and unsaturated compounds having an epoxy group, such as glycidyl acrylate and glycidyl methacrylate.

The resin beads having an average particle diameter of about 0.2 to 0.955 mm can be obtained by suspension polymerizing from the styrene type monomers described above using water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyvinyl pyrrolidone and the like and slightly soluble inorganic salts such as magnesium pyrophosphate, calcium tertiary phosphate and the like, in the presence of a surface active agent. The monomers may be added in one portion or little by little to the aqueous medium.

The expanded resin beads preferably have an apparent specific density of 0.01 to 0.2. An apparent specific density of greater than 0.2 is not preferable because the weight of the resulting cushioning body is increased, while an apparent specific density of smaller than 0.01 is not preferable either because the strength of the expanded resin beads filling in the cushioning bodies is decreased. The apparent specific density is more preferably 0.015 to 0.05.

In the expanded resin beads, the shape of bubbles constituting the beads, the diameter of the bubbles, the number of the bubbles, and the like are not particularly limited insofar as the effect of the present invention is not deteriorated. In particular, the present inventors found that the expanded resin beads each having 25 to 80 bubbles/mm (unit length) in the direction of diameter when cut along a face containing the diameter thereof lead to further improvements in the performance of the cushioning body. Less than 25 bubbles/mm are not preferable because the fluidity of the beads is easily deteriorated and an unusual sound easily occurs, while 80 or more bubbles/mm are not preferable either because the thickness of a bubble membrane maintaining a bubble is too thin, thus reducing the strength of the expanded resin beads. The method of measuring the number of bubbles is described in the Examples.

In the expanded resin beads, the content of the fluidity accelerator (fluidizing agent) is 0.4 to 1.5 parts by weight based on 100 parts by weight of the expanded resin beads. This fluidity accelerator functions as a lubricant for the expanded resin beads, and can act in preventing occurrence of an unusual sound attributable to the expanded resin beads rubbing mutually upon fluidization. The content of the fluidity accelerator in the present specification means the amount of the fluidity accelerator actually contained in the fillers, but not the amount thereof as the starting material added to the resin beads.

The fluidity accelerator includes, for example, salts of fatty acids (stearic acid, lauric acid, palmitic acid) and metals (magnesium, calcium, zinc, barium, aluminum), and calcium carbonate, polyethylene wax and the like. Among these, zinc stearate, calcium stearate, and magnesium stearate are particularly preferable. If the content of the fluidity accelerator is lower than 0.4 part by weight, the fluidity may be insufficient and its effect on prevention of occurrence of an unusual sound tends to be insufficient, while even if the fluidity accelerator is contained in an amount of higher than 1.5 parts by weight, no further effect can be expected. The fluidity accelerator is contained more preferably in an amount of 0.45 to 1.2 parts by weight.

The method of incorporating a fluidity accelerator into the expanded resin beads includes, for example, a method of incorporating it into monomers for forming the expanded resin beads, a method of incorporating it into the resin beads before impregnation with an expanding agent and after completion of polymerization, a method of incorporating it into the expandable resin beads impregnated with an expanding agent and a method of incorporating it into the expanded resin beads after expanding. In particular, the method of incorporating it into the expandable resin beads is preferable from the viewpoint of easy production of the expanded resin beads.

The fluidity accelerator may be incorporated in any shapes such as powder, film and the like into the expanded resin beads.

When the fluidity accelerator is powder, its average particle diameter is preferably smaller than the average particle diameter of at least the expanded resin beads, and is specifically in the range of 0.1 to 100 μm, more preferably in the range of 0.1 to 30 μm. From another viewpoint, the average particle diameter of the fluidity accelerator is preferably in the range of about 1/1000 to 1/10 based on the average particle diameter of the expanded resin beads. The shape of the powder may be spherical, needle-like, scaly, bulky, amorphous and the like. Further, polybutene, polyethylene glycol, silicone oil and the like may be added as the spreading agent to the fluidity accelerator added. The amount of the spreading agent added is preferably 1 to 20 parts by weight based on 100 parts by weight of the fluidity accelerator added.

When the spreading agent is not used, the expanded resin beads are stirred preferably under conditions regulated suitably such that a predetermined amount of the fluidity accelerator is contained therein. For example, the beads are stirred preferably under relatively high shear force by using a stirring machine such as a Henschel mixer. When the spreading agent is used, the spreading agent facilitates incorporation of the fluidity accelerator into the expanded resin beads, and thus the fluidity accelerator can be incorporated into the expanded resin beads by stirring under more moderate conditions than when the spreading agent is not used.

In the case of film, the film can be formed for example by a method of dissolving the fluidity accelerator in a solvent, spraying the resulting solution onto the resin beads and drying it or by a method of dipping the resin beads in the solution and then drying it. Further, when the fluidity accelerator is melted at a relatively low temperature, the film can also be formed by coating the resin beads with or dipping them in the melted fluidity accelerator.

If necessary, additives such as a flame retardant, a flame retardant assistant, a particle size distribution regulator and the like may be suitably added, or rubber components such as butadiene rubber, styrene-butadiene rubber and the like may be mixed. Further, polyoxyethylene alkylphenol ether, stearic acid monoglyceride and the like may also be used as antistatic agents. Together with these other agents, a low amount of a spreading agent such as polybutene, ethylene glycol or silicone oil may be added.

Further, the styrene-based expanded resin beads can be produced by expanding the thus obtained styrene-based expandable resin beads by steam heating and the like. As the expanding method, a method of expanding the beads for example by steam heating and the like with a cylindrical preliminary expanding machine can be used. An expansion ratio of the styrene-based expanded resin beads in present invention are preferably at about 5- to 100-fold (apparent specific density 0.01 to 0.2). In particular, the beads expanded at about 20- to. 65-fold (apparent specific density 0.015 to 0.05) can give a particularly excellent feel to cushioning bodies.

The aroma-containing beads comprise an aromatic and carrier beads for bearing the aromatic. Examples of the carrier beads include beads having a base made of silica gel, zeolite, activated carbon, magnesium powder, polyethylene, polystyrene, polypropylene, polyvinyl acetate, polymethacrylate, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer or the like.

The aromatic is not particularly limited, and various aromatics may be used. For example, widely used floral-based, citrus-based, fruit-based, green-based and cosmetic-based natural aromatics, synthetic aromatics and mixtures of these may be used. The amount of the aromatic to be blended is preferably 1 to 20% by weight based on the aromatic containing beads as a whole, more preferably 5 to 15% by weight. The amount of smaller than 1% by weight is not preferable because the aroma is hardly perceived. The amount of greater than 20% by weight is not preferable because a sufficient relaxation or aromatherapy effect is hardly obtained.

The amount of the aromatic to be blended can be suitably adjusted according to the kind of aromatic. That is, if the aromatic is of a kind in which a strong aroma is preferable, the amount can be set to be great, while if the aromatic is of a kind in which a faint aroma is preferable, the amount can be set to be small.

The amount of the aroma-containing beads used in the fillers is preferably 1 to 30 parts by weight based on 100 parts by weight of expanded resin beads. The amount of smaller than 1 part by weight is not preferable because the aroma is weak. The amount of greater than 30 parts by weight is not preferable because the touch of the cushioning body is degraded.

Given that the average particle diameter of the expanded resin beads is defined as D, an average particle diameter Da of the aroma-containing beads is preferably D to 10D, more preferably D to 5D. Da of smaller than D is not preferable because the aroma-containing resin beads leak out from a crevice formed in the bag or from between fibers and because the aroma duration is shortened. Da of greater than 10D is not preferable because the touch of the cushioning body is degraded. The method of measuring the average particle diameter Da is described in the Examples.

A value obtained by dividing the apparent specific density of the expanded resin beads by the apparent specific density of the aroma-containing beads is preferably 0.025 to 0.1. If the value is in this range, the aroma-containing beads can be dispersed relatively uniformly in the expanded resin beads. Further, if there is a suitable difference in apparent specific density between the aroma-containing beads and the expanded resin beads, aroma-containing beads close to the bag inside surfaces move selectively in the expanded resin beads when the cushioning body is touched, so that the feel is not degraded. The value of smaller than 0.25 is not preferable because the apparent specific density of the aroma-containing beads is too great compared with that of the expanded resin beads, so that the aroma-containing beads are biased to a lower position of the cushioning body to degrade the touch of the cushioning body. The value of greater than 0.1 is not preferable because the touch of the cushioning body tends to be degraded. The method of measuring the apparent specific density is described in the Examples.

Further, if the carrier beads are made of a non-perfect-spherical substance such as silica gel, the touch of the cushioning body is degraded in some cases. To avoid the degradation, the carrier beads are preferably in a form as close to a perfect sphere as possible, and more preferably the average particle diameter (major diameter) Da of the aroma-containing beads and the minor diameter Ds thereof satisfy the equation 0.6≦Ds/Da≦1. The method of measuring the average particle diameter Da and minor diameter Ds is described in the Examples.

The method of providing the carrier beads with the aromatic is not particularly limited and any known method may be used. The method of providing the carrier beads with the aromatic includes, for example, a method of simply putting the carrier beads into a solution or dispersion of an aromatic to impregnate the carrier beads with the solution and then upon necessity of removing the solvent.

The method of mixing the expanded resin beads with the aroma-containing beads is not particularly limited and a method employing a known stirrer for mixing may be used.

The bag usable in the faintly aromatic cushioning body of the present invention can make use of a cloth made of a stretchable material, chemical fibers, silk, cotton and the like. In particular, the bag is made preferably of the stretchable material in order to confer an excellent feel. The stretchable material preferably has 30 to 300% stretchablity. The stretchable material is most preferably spandex (elastic fibers of polyurethane), for example, which has elasticity. By using the bag described above, the following effects are demonstrated.

First, the expanded resin beads have the effect described above, that is, the expanded resin beads have easily fluidizing and sliding properties upon application of very small strength, thus providing the cushioning body with significant improvement in the touch and feel. A stretching material is used for the bag so that when a part of the cushioning body is compressed, the packed beads can move from the compressed region to the rest of the bag, whereupon the rest of the bag can be stretched and deformed to accommodate the moving beads, thus broadening the allowable range of movement of the beads. In addition, the cushioning body having a better feel can be provided due to the synergistic effect of the expanded resin beads and the bag.

The above-described expanded resin beads to be packed in the cushioning body are used as fillers for preventing generation of an unusual sound, for exhibiting a preferable feel and for satisfying permanent cushioning properties, and in a more preferable mode, the cushioning bodies are provided with a double fastener capable of opening and closing, thus preventing these fillers from leaking out from the bag. Further, the bag constituted to be a double bag is effective.

Also, the bag can be constituted by introducing a plurality of bags charged with the fillers into one large bag. In this case, the fillers in a plurality of bags may have different feels from one bag to another.

According to the present invention, in particular, the filler is preferably sealed into the bag so as to have a volume 1.1 to 3.5 times the internal volume of the bag made of the stretchable material. By sealing as the filler the expanded resin beads and the aroma-containing beads in a volume greater than the internal volume of the bag made of the stretchable material, the expanded resin beads and the aroma-containing beads are hardly biased in position and a better feel and prevention of deformation of the cushioning body can be realized. When the volume of the filler is smaller than 1.1 times the internal volume of the bag, a soft cushioning body is given and thus no remarkable effect is produced from the viewpoint of deformation prevention. The volume of the filler greater than 3.5 times the internal volume of the bag is not preferable to degrade the feel and touch. A preferable volume of the filler is 1.3 to 2.5 times the internal volume of the bag.

By using the bag made of the stretchable material described above, the following effects are demonstrated. A stretching material is used for the bag so that when a part of the cushioning body is compressed, the packed beads can move from the compressed region to the rest of the bag, whereupon the rest of the bag can be stretched and deformed to accommodate the moving beads, thus broadening the allowable range of movement of the beads. In addition, the cushioning body having a dramatically improved feel can be provided.

The amount of the fillers to be sealed is changed according to the stretchability of a material for the bag, reaction given when the bag material is stretched, shape of the cushioning body, stress applied to the cushioning body and application of the cushioning body. For example, when the bag has a great stretchability, a greater amount of fillers is needed than when the bag has a small stretchability. When a great stress is applied to the cushioning body, a greater amount of fillers is also needed than when a small stress is applied to it. When the emphasis lies on a seat comfort, the amount of the fillers should be relatively small, whereas when the emphasis lies on a suitable stability in the shape of the cushioning body as in the case of the application to a chair and the like to prevent deformation of the cushioning body, the amount of the fillers should be relatively large.

The faintly aromatic cushioning body of the present invention can serve preferably as a bed, a mattress, a pillow, a stuffed toy, a cushion, a toy, a cushioning medium, a sealed material, a soundproofing material, a thermal insulating material and the like.

When the cushioning body is used as a cushioning body ridden or hold by a person, an effect from the above touch, aroma and the like gives suitable stimuli to the five senses of the person, which would generate much alpha wave in the brain. As a result, it can be expected to provide a cushioning body making the person more easily relaxing.

Further, a surface of the bag may be printed with e.g. a face having eyes, nose, and mouth and the like. In this case, the face can give expressions by the properties of the expanded resin beads and the bag (called an animation effect).

EXAMPLES

Hereinafter, the present invention is described in more detail by the Examples and Comparative Examples, which however are not intended to limit the present invention. The methods of measuring various values given in the Examples and the Comparative Examples are described below.

<Method of Measuring a Solvent>

To a solution of the expanded resin beads in dimethylformamide, an internal standard solution (cyclopentanol) is added, and a solvent in the resulting solution is measured by GC. Peaks of styrene, toluene, ethylbenzene, cumene, xylene, and n-propylbenzene that are measured in the above manner are specified using a standard sample prepared by mixing internal standard solutions in a specific ratio.

-   GC: GC-14A manufactured by Shimadzu Corporation -   Column: PEG-20M PT 25% 60/80 (2.5 m) -   Column temperature: 105° C. -   Detector (FID) temperature: 220° C.     <Method of Measuring the Average Particle Diameter D of the Expanded     Resin Beads>

The average particle diameter D is the particle diameter (median diameter) at a cumulative weight of 50% on a cumulative weight distribution curve prepared from the results of classification of the beads by JIS standard screens having a screen opening size of 4.00 mm, an opening size of 3.35 mm, an opening size of 2.80 mm, an opening size of 2.36 mm, an opening size of 2.00 mm, an opening size of 1.70 mm, an opening size of 1.40 mm, an opening size of 1.18 mm, an opening size of 1.00 mm, an opening size of 0.85 mm, an opening size of 0.71 mm, an opening size of 0.60 mm, an opening size of 0.50 mm, an opening size of 0.425 mm, an opening size of 0.355 mm, an opening size of 0.300 mm, an opening size of 0.250 mm, an opening size of 0.212 mm and an opening size of 0.180 mm, respectively.

<Method of Measuring the Average Particle Diameter (Major Diameter) Da and Minor Diameter Ds of the Aroma-Containing Beads>

The major diameters and minor diameters of ten aroma-containing beads are measured using DEJITALNOGISU EM3001 manufactured by NAKAMURASEISAKUSYO in Japan and averaged to give Da and Ds, respectively.

<Method of Measuring the Apparent Specific Density>

An apparent specific density-measuring cup (internal volume, 100 ml) in a powder tester (manufactured by Hosokawa Micron Co., Ltd.) is charged gently with the expanded resin beads or with the aroma-containing beads, and the surface of the expanded resin beads is cut flat on the cup by means of its equipped blade standing vertically, and the weight is measured with a pan balance and then divided by 100. The value thus obtained is referred to as apparent specific density.

<Feel Test>

A double bag (columnar shape, size 18 cm (diameter)×30 cm, internal volume 7.63 L) with a double faster, made of a stretchable material spandex is charged with expanded resin beads shown in Table 1 and aroma-containing beads shown in Table 1, and its feel is evaluated by 10 examiners. ⊚ is given when 8 or more examiners judged the bag to have a good feel, ◯ is given when 6 or 7 examiners judged so, and X is given when 5 or less examiners judged so, and a cushioning body judged to have a good feel by 6 or more examiners is regarded as an acceptable product.

<Aroma Test>

The expanded resin beads and the aroma-containing beads are charged and the resulting cushioning body is stored in an oven maintained at 40° C. to test the aroma of the cushioning body (directly after the charging and one month after the charging). The aroma is judged by its intensity. In the case where there is no smell other than a good aroma, ⊚ is given when there is a strong aroma, ◯ is given when there is a aroma, Δ is given when there is a faint aroma, and X is given when there is no aroma, and in the case where there is a smell other than a aroma, XX is given. A cushioning body given ⊚ or ◯ is regarded as an acceptable product.

Example 1

120 g of tricalcium phosphate (trade name: calcium tertiary phosphate, manufactured by Taihei Kagaku Co., Ltd.), 0.24 g of sodium hydrogen sulfite and 0.24 g of potassium persulfate were introduced into a 100-L autoclave, and 133 g of benzoyl peroxide (purity 75%, trade name: Niper BW, manufactured by Nippon Oil and Fats Co., Ltd.), 56 g of t-hexylperoxy isopropyl monocarbonate (purity 90%, trade name: Perhexyl I, manufactured by Nippon Oil and Fats Co., Ltd.), 40 kg of deionized water and 40 kg of styrene monomer which contains a solvent of 264 ppm other than styrene were further introduced into the mixture, dissolved and suspended under stirring to prepare a suspension.

Then, the styrene monomer was subjected under stirring at 200 rpm to polymerization reaction in the autoclave at 90° C. for 8 hours and then at 125° C. for 3.5 hours. After the reaction was finished, the reaction mixture was cooled, removed from the autoclave, centrifuged and dried to give styrene resin beads.

Separately, 2000 g of water, 12 g of magnesium pyrophosphate, 0.3 g of sodium dodecylbenzenesulfonate and 0.1 g of dilauryl-3,3′-thiodipropionate were introduced into a 5-L autoclave to prepare an aqueous medium. 2000 g of sifted 0.25 to 0.5 mm styrene resin beads were added to this aqueous medium and stirred at 300 rpm.

Then, the temperature was raised to 110° C., and while this temperature was maintained, 180 g of pentane was injected into the autoclave, and the resin beads were impregnated with the pentane for 1.5 hours and cooled to give expandable styrene resin beads.

The expandable styrene resin beads were uniformly heated with water vapor with a batch type preliminary expanding machine having an internal volume of 50 L, to give expanded resin beads having an average particle diameter D of 1.0 mm and an apparent specific density of 0.033. The resulting expanded resin beads were dried in a drying chamber at 30° C. for 24 hours. The expanded resin beads contained a residual solvent of 205 ppm.

Further, 70% by weight of silica gel (HAIYANG SILICAGEL TYPE B SPHEREQ/O₂HHJO10-1999) manufactured by QINGDAO HAIYANG CHEMICAL CO., LTD.), 10% by weight of alcohol, 10% by weight of an orange-based aroma and 10 parts by weight of dipropylene glycol were introduced into a resin bag, which was then hermetically sealed and manually shaken so as not to disintegrate the silica gel. Then, the bag was opened and while the bag was opened, the silica gel was dried at a room temperature of 25° C. for three hours.

A stretchable material spandex double bag (columnar shape, size 18 cm (diameter)×30 cm, internal volume 7.63 L) with a double fastener was charged with 28 g of the resulting aroma-containing beads (having an apparent specific density of 0.71, an average particle diameter (major diameter) Da of 4 mm and a minor diameter Ds of 3.8 mm) and with 280 g (8.4 L) of the above expanded resin beads to give a faintly aromatic cushioning body. Then, the feel test and the aroma test were conducted. The results are shown in Table 1.

Example 2

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that the expanded resin beads were dried at 60° C. The results are shown in Table 1.

Example 3

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that the expanded resin beads were dried at 60° C. for seven days. The results are shown in Table 1.

Example 4

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that styrene monomer having a solvent content of 210 ppm other than styrene was used. The results are shown in Table 1.

Example 5

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that styrene monomer having a solvent content of 432 ppm other than styrene was used. The results are shown in Table 1.

Example 6

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that the amount of the aroma-containing beads was changed to 8.4 g. The results are shown in Table 1.

Example 7

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that the amount of the aroma-containing beads was changed to 70 g. The results are shown in Table 1.

Example 8

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that the average particle diameter Da of the aroma-containing beads was changed to 8 mm. The results are shown in Table 1.

Example 9

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that the amount of the expanded resin beads was changed to 240 g (7.2 L). The results are shown in Table 1.

Example 10

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that 0.25 to 0.34 mm sifted styrene resin beads were used. The results are shown in Table 1. The amount of residual solvent in the expanded resin beads was 195 ppm and the average particle diameter D was 0.85 mm.

Comparative Example 1

A faintly aromatic cushioning body was obtained in the same manner as Example 4 except that 1 g of toluene was added at the time of impregnation to give styrene-based expanded resin beads having a solvent content of 729 ppm. The results are shown in Table 1. The amount of residual solvent in the expanded resin beads was 592 ppm. Directly after the charging, there was a faint solvent smell as a result of a mixture of an aroma of an aromatic and a smell of residual styrene monomer. However, one month after the charging, the residual solvent volatilized to 125 ppm and there was no solvent smell.

Comparative Example 2

A faintly aromatic cushioning body was obtained in the same manner as Example 4 except that 2 g of ethylbenzene was added at the time of impregnation to give styrene-based expanded resin beads containing a solvent of 1199 ppm. The results are shown in Table 1. The amount of residual solvent in the expanded resin beads was 1027 ppm. Directly after the charging, there was an unpleasant odor as a result of a mixture of an aroma of an aromatic and a smell of residual styrene monomer. However, one month after the charging, the residual solvent volatilized to 365 ppm and there was no unpleasant odor.

Comparative Example 3

A faintly aromatic cushioning body was obtained in the same manner as Example 4 except that 2 g of toluene and 2 g of ethylbenzene were added at the time of impregnation to give styrene-based expanded resin beads having a solvent content of 2184 ppm. The results are shown in Table 1. The amount of residual solvent in the expanded resin beads was 1984 ppm. Directly after the charging, there was a strong unpleasant odor as a result of a mixture of an aroma of an aromatic and a smell of residual styrene monomer. Further, one month after the charging, the amount of residual solvent was 842 ppm and there was an unpleasant odor as a result of the mixture of an aroma of an aromatic and a smell of residual styrene monomer.

Comparative Example 4

A faintly aromatic cushioning body was obtained in the same manner as Example 1 except that 0.5 to 0.7 mm sifted styrene resin beads were used. The results are shown in Table 1. The amount of residual solvent in the expanded resin beads was 258 ppm and the average particle diameter D was 1.6 mm. TABLE 1 Expanded resin beads Aromatic-containing beads Aroma test Average particle Solvent Average particle Directly One month diameter Charging content diameter Da Charging after after D (mm) amount (g) (ppm) (mm) amount (g) Feel test charging charging Example 1 1 280 205 4 28 ⊚ ⊚ ◯ Example 2 1 280 165 4 28 ⊚ ⊚ ◯ Example 3 1 280 45 4 28 ⊚ ⊚ ◯ Example 4 1 280 153 4 28 ⊚ ⊚ ◯ Example 5 1 280 356 4 28 ⊚ ⊚ ◯ Example 6 1 280 205 4 8.4 ⊚ ⊚ ◯ Example 7 1 280 205 4 70 ◯ ⊚ ⊚ Example 8 1 280 205 8 28 ◯ ⊚ ⊚ Example 9 1 240 205 4 28 ◯ ⊚ ◯ Example 10 0.85 280 195 4 28 ⊚ ⊚ ◯ Comparative 1 280 592 4 28 ⊚ XX ◯ Example 1 Comparative 1 280 1027 4 28 ⊚ XX ◯ Example 2 Comparative 1 280 1984 4 28 ⊚ XX XX Example 3 Comparative 1.6 280 258 4 28 X ⊚ ◯ Example 4

From Examples 1 to 9 and Comparative Examples 1 to 3, it was found that if the solvent content is 400 ppm or less, a preferable aroma can be produced even directly after the charging and can be maintained for a long time.

From Example 8, it was found that when the average diameter Da of the aroma-containing beads is large, a preferable aroma can be maintained for a longer time.

According to the present invention, the expanded resin beads having a solvent content as low as 400 ppm or less are used as fillers. Accordingly, the relaxation or aromatherapy effect being inhibited by the solvent smell mixed with the aromatic agent smell can be prevented.

Further, according to the present invention, the expanded resin beads used as the fillers have an average particle diameter as extremely small as 0.4 to 1.4 mm. The expanded resin beads easily slid mutually by very small strength. Accordingly, it is possible to obtain a cushioning body which does not provide a discomfort caused by an unusual sound attributed to the movement of the expanded resin beads and which exhibits preferable touch and feel.

When the average particle diameter D of the expanded resin beads and the average particle diameter Da of the aroma-containing beads satisfy the equation D≦Da≦10D, it is possible to obtain a cushioning body in which leakage of the aroma-containing beads from a crevice formed in the bag or from between fibers is prevented, which has a long-lasting aroma and which exhibits more preferable touch and feel.

When the aroma-containing beads are used in the amount of 1 to 30 parts by weight based on 100 parts by weight of the expanded resin beads, it is possible to obtain the cushioning body which has a long-lasting aroma and which exhibits preferable touch and feel.

When a stretching material is used for the bag, the packed beads can move from the compressed region to the rest of the bag when a part of the cushioning body is compressed, whereupon the rest of the bag can be stretched and deformed to accommodate the moving beads, thus broadening the allowable range of movement of the beads.

When the surface of the bag is printed with e.g. a face having eyes, nose, and mouth and the like, the face can give expressions (called an animation effect). When the cushioning body is used as a cushioning body ridden or hold by a person, suitable stimuli is given to the skin of the person, which would generate more alpha wave in the brain. As a result, it can be expected to provide a cushioning body making the person more easily relaxing. 

1. A faintly aromatic cushioning body comprising: a mixture of expanded resin beads and aroma-containing beads, the expanded resin beads having a solvent of 400 ppm or less and an average particle diameter of 0.4 to 1.4 mm, wherein the mixture of expanded resin beads and aroma-containing beads is used as a filler into a bag.
 2. The faintly aromatic cushioning body of claim 1, wherein the solvent is styrene, toluene, ethylbenzene, cumene, xylene or n-propylbenzene.
 3. The faintly aromatic cushioning body of claim 1, wherein an average particle diameter D of the expanded resin beads and an average particle diameter Da of the aroma-containing beads satisfy the equation D=≦Da≦10D.
 4. The faintly aromatic cushioning body of claim 1, wherein the aroma-containing beads are used in the amount of 1 to 30 parts by weight based on 100 parts by weight of the expanded resin beads.
 5. The faintly aromatic cushioning body of claim 1, wherein the bag is made of a stretchable material.
 6. The faintly aromatic cushioning body of claim 5, wherein the filler is sealed into the bag so as to have a volume 1.1 to 3.5 times the internal volume of the bag made of the stretchable material. 